​Since I started diving 14 years ago, coral reefs have fascinated me. I am a third year PhD student in the Baum Lab at the University of Victoria. What started as diving for fun with my family turned into a career, and now, for my dissertation, I am studying deviant corals – those corals that can beat the heat and survive in ocean conditions that are less than ideal.

Some people imagine corals as colorful rocks, sitting on the bottom of the ocean. Corals actually do build a limestone skeleton as they grow – but corals are much more than this.​So, if corals can grow… does that mean they are animals? Yes! Corals are Cnidarians and are closely related to jellyfish. But corals are even more than that…

Close-up of an Acropora coral colony. You can see the coral animal sticking out from the skeleton if you look really closely. (Kristina Tietjen)

Corals are miniature ecosystems. The coral animal partners with tiny plants (single-celled algae) that live inside the coral’s tissues. These tiny plants act like solar panels. They absorb light from the sun and photosynthesize (just like your house plants), and in return for a safe place to live they feed their coral host. Corals also host a myriad of other microbes, which help the coral live and grow. These other microbes work similarly to the human gut bacteria that help you digest the food you eat. Some combinations of corals, algae, and microbes are deviant combinations – they grow faster and survive better.

Close up of another Acropora coral colony on Kiritimati Island. (Kristina Tietjen)

What happens to these miniature ecosystems when El Niño turns up the heat? A water temperature increase of just a few degrees can be devastating to coral reefs. When a large environmental disturbance like El Niño occurs, the coral ecosystem can start to break down because for many corals the water is simply too hot to survive. Algae and good microbes get kicked out of the coral, and the coral suffers (see NOAA's website for more info). ‘Bad’ microbes can enter into the ecosystem and wreak havoc on the coral. However, there are some deviant corals – miniature coral ecosystems that have the ideal combination of animal, algae, and microbes. These deviant corals can survive, and even thrive when water temperatures are too hot for most other corals to handle.

Deviant coral? Healthy coral on the right, and for contrast, an unhealthy bleached coral on the left. ​Photo taken on Kiritimati during the El Niño bleaching event (Baum Lab, July 2015)

The focus of my PhD is to better understand these deviant corals. Why do some corals survive, while others perish in the heat? By returning to Kiritimati Island in March (help support our research here!), our team will be looking for the survivors – those corals who beat the odds. I’m not sure what we’ll find on this expedition, but I am excited for the opportunity to return and check up on our deviant corals. After we finish up with our diving field expedition to Kiritimati, we’ll use advanced genetic sequencing techniques to figure out what makes deviant corals special. If we can learn what makes these corals unique, we can better understand how to conserve these fascinating ecosystems.